Spline shaft grinding machine



July 2 1940. R. WESTENBERGER ET AL SPLINE SHAFT GRINDING uAcn'nlE FiledMay 2, 1939 '7 Sheets-She'et -1' Fig-.

Inventors: Rudolf 9103601050 ,0 1. U0 wn H u. m mw fave/5 Attorney.

July 2, 1940. R. WESTENBER GER ET AL 2 SPLINE SHAFT GRINDING MAQHIIIEFiled May 2, 19:59 7 Sheets-Sheet 2 Fig.3

7nuen/ors: Ruao/fh/es/enbcrger h/a/ler Haqff Willy 689,91, WM m6 Al/omeyJuly 2, 1940. R. WESTENBERGER tr AL 2.0. 3

SPLINE SHAFT GRINDING MACHIIE Filed May 2, 1939 I 'T Sheets-Sheet 3I"In!llllllllllllJl/llll[I'll/111111111111 Jnwenfon: Rudolf mumm Wall!!-Hquffo Willy awgi Attomoy.

July 2. 1940 R. WESTENBERGER Er AL' 2,205,492

SPL-INE SHAFT emm'ame MACHINE Filed May 2, 1939 '7 She etS-Sheet 4"Jnnnfofd': Rudd} Wutmbergir Walter Hauffc Willy Georg M Attorney.

July 2,1940. R. WESTENBERGER El AL 3 SPLINE SHAFT GRINDING MACHI'E FnedMay 2-, 19:59 7 Shets-Sheet s Fig. 5

IIImInfOI-J Rudolf wastcnbergcr Walter Hqujfa Willy Georgi ARM-My July2, 1940. R. WESTENBERGER IEI' AL 2,205,492

SPLINE SHAFT GRINDING MACHINE 7 Sh eets-Sheet'6 Filed May 2, 1939Inventors: Rudolf Wutcnberger Waller Haufio wi Georgi I 2, 9 R.WESTENBERGER ET AL 2,206,492

SPLINE SHAFT GRINDING MACHINE Filed May 2, 1959 7 Sheets-Sheet 7 5 L 5 0v3 5 a I ll. 1 I JIM!" I C My I m V 7 5' 7 v H 0w 1 I 9 4 H inventor-$1Rudolf Wufgnbe rgcr mm mm WM Ma Atformy Patented July 2, 1940 UNITEDSTAT-ES 2,205,492 SPLINE smr'r oanmme MACHINE Rudolf Westenberger,Walter Hauife, and Willy Georgi, Chemnitz, Germany, assignors to J. E.Reinecker, Aktien-Gesellschaft, Chemnitz, Germany Application May 2,1939, Serial No. 271,302 In Germany November 30, 1932 4 Claims. (01.51-92) Our invention relates to automatic machine tools for grindingsplinedshafts, cutting the teeth of gear wheels, and the like, andproducing in general circumferentially profiled pieces of work, of whichthe blanks in the course of the machining operations are axiallyreciprocated relatively to the tool, and are step by step angularlyindexed relatively to the tool.

The invention relates more especially to improvements in automaticmachine tools of the type and for the purposes set forth hereinafterbriefly called spline shaft grinding machines, in which the saidreciprocating and indexing movements are both performed by hydraulicallyoperated mechanisms. Spline shaft grinding machines having hydraulicallyoperated mechanisms for performing the reciprocating and indexingmovements concerned are nowadays preferred in many cases, because-theirhydraulic mechanisms are capable of being more easily controlled by theoperator, namely, readjusted in a continuous and highly exact manner asto their working speed, for

to the grinding wheel, by means of simple throttle valves, incontradisti'nction to machine tools, in which the working speed ofmechanically driven mechanisms can be adjusted only intermittently andby degrees or steps.

On the other hand the hydraulically operated mechanisms of spline shaftgrinding machines are subject to leakage resulting in inaccurateindexing and even in damage to the tool or blank causing longinterruptions in the working of the machine.

The principal object of this invention is to provide an improvedhydraulically operated spline shaft grinding machine of thetype'concerned, in which the mechanism for reciprocating the 40 blankrelatively to the tool is cooperatively associated with and functionallysubordinated to the indexing mechanism in such manner, that thereciprocating mechanism is not unlocked and set free for starting upon afresh working stroke until the indexing mechanism has been properlyre-set and locked in its fresh working position.

In other words the invention aims at avoiding damaging the workpiece ofthe machine tool or both in the event of the hydraulically actuatedindexing mechanism not operating accurately on account of leakage in theconduits, namely at positively preventing the table to start upon ainstance as to the feeding of the blank relatively the control elementsand to reduce the wear of the delicate parts of the indexing mechanismfor the purpose of facilitating their smooth operation and ensuringgentle and highly accurate indexing operations. I

Furthermore the inventionaims at reducing the number of the componentparts of the indexing mechanism, especially the number of liquidconduits, so as to reduce the sources of defects.

Finally, the invention aims at providing improved means for regulatingthe speed in the indexing operationsincluding turning of the indexplate, and engagement of the pawl-so as to afford coarse indexing to beperformed as quickly as fine indexing. 15

Other objects of the invention will become apparent to practitioners inthis field as the description proceeds.

The nature and scope of the invention are briefly outlined in theappended claims-and will 29 be more fully understood from the followingspecification taken together with the accompanying drawings, in whichspline shaft grinding machines re-designed according to this inventionare shown by way of examples: 25

Fig. 1 is a. fragmentary front elevation showing the re-designed machinewith its most important parts,

Figs. 2 and 2a are electric wiring diagrams showingthe main pawl of theindexing mecha- 6 nism in different positions,

Fig. 3 shows the indexing mechanism on a larger scale and in sectionvertically taken through its main axis,

Fig. 3a is a cross-section of the indexing mech- 35 anism taken on lineIIIa-IIIa of Fig. 3,

Fig. 4 is a front elevation of-,the indexing mechanism with casing coverremoved,

Figs. 5 and 5a show in section taken on line V--V of Fig. 4 a time-relayprovided in the in- 40 dexing mechanism and its hydraulic motors for theindex pawl and for the index plate in differ. ent operating positions,

Fig. 6 is a section vertically taken through the table and indexingcontrol mechanism on line 45 Fig. 7 is a section horizontally takenthrough the principal oscillatable control member on line VI[VII of Fig.6; Y

Fig. 8 shows some partsiof the control member 50 shown in Fig.6 insection;

Fig. 9 is a cross section vertically taken through the principal controlmember on line IX-IX of Fig. 6 and showing also an electromagneticallyoperated shut off valve associated therewith; 5'5

Figs. 10 to 15 are cross sections through the I principal control membertaken on lines XX to XVXV of Fig. 6;

Fig. 16 is a diagrammatic general view of a machine modifiedstructurally, wherein the reciprocating table carries the grindingwheel, whereas the indexing mechanism and the workpiece are stationary.

The spline shaft grinding machine re-designed with the objects in viewoutlined above comprises:

A table 2|, reciprocable in the direction of arrows 25, which isslidably mounted on the machine bed 20 under a grinding wheel 24; thetable 2| carries a workpiece headstock structurally associated with anindexing mechanism 22 and the workpiece 23 which is rotated by means 'ofa catch 23. The table 2|i and the indexing mechanism 22 are bothoperated by hydraulic pressure produced by an oil pump 26 driven by aprime mover M (Figs. 2, 2a) the oil is sucked from storage tank 3|through conduit 21 and forced 'into a conduit 28 provided with apressure relief valve 29 loaded by a spring 29'; by means of a checkvalve 30 operable by hand the oil under pressure can be turned on andoff, while the oil pump 26 is running. The oil conduit 20 divides intoseveral branches within a control block 40, allowing the oil to passfrom the conduit 29 through a throttle valve 19 (Fig. 6) operable byhand into two passages and 9|, and, before reaching the throttle valve19, into conduits 32 and 33, of which the conduit 32 leads to a shut-oilvalve 31 (Fig. 9) loaded by a spring S, whereas the conduit 33 dividesup into two additional passages 34 and 35 which both lead to a cock plug42.

The shut-off valve 31 (Figs. 1, 9) has a longitudinal channel 36 and anannular recess I04 and isconnected to an electromagnet I03; conduit 39leads from valve 31 to a cock plug 4|, and another conduit 39 leads to adischarge channel 51; 39' is a pressure relief channel provided incontrol block 40 and leading from conduit 39 to the front end of theshut-off valve 31. v

' Both cock plugs 4| and 42 (Figs. 6, 'l and 81 are arranged coaxiallyin a bore hole of the control block 40; they are rigidly interconnectedby a spline shaft 43; a sleeve 44 is slidably arranged on said splineshaft 43 between said cock plugs and participates in their rotarymotion. The cock plug 4| has a circumferential groove 93 (Fig. 9) and alongitudinal groove 56 (Figs. 6 and 8),

-which is open at the end adjacent the sleeve 44 (Fig. 8); cock plug 42has two peripheral passages 94 and (Figs. 7, 14, 15) and a longitudinalpassage 55, whereas the sleeve 44 has two peripheral recesses 48 and 52.v

The cock plugs 4| and 42 are turned around jointly with the sleeve 44 bymeans of an adjustable dog or abutment 46 (Fig. 1) fixed on the table 2|and acting on a lever 45 indicated in dash lines in Fig. I. Otherpassages 51, 53, 60, 6| and 62 (Fig. 6) in the control block 40 areconnected with a discharge passage 54, a spring loaded pressure ballvalve .99 being arranged in the discharge of the passages 6|, 62 whichunite to form a passage 63; the spring 99' of the ball valve 89 isweaker than the spring 29' of the pressure relief valve 29 (Fig. 1).

In addition to the above mentioned passages,

the control block 40 has passages 49, 59 (Fig. 7) which unite to form apassage 91 leading to the right sid of the piston 50 operating the table2| (Fig. 1), hich is rigidly connected therewith at 2I'passages 51, 58(Fig. '7) which'unite to form a passage 99 leading to the left side ofthe working piston 50and a passage 64 (Fig. '7) connected to theindexing mechanism by means of a pipe 64' (Fig. 1).

The indexing mechanism The indexing mechanism 22 comprises an indexplate (Figs. 3 and 4) which is exchangeably mounted on the workpiecespindle 92 and in which an oscillatably mounted index pawl 9| engages.Keyed on the workpiece spindle 92 is a ratchet wheel 96 in which a pawlengages which is mounted on a toothed wheel 94 and kept constantly incontact with the ratchet wheel 99 r by a spring not shown on thedrawings.

A rack 93 (Fig. 3a) movable perpendicular to the plane of the drawingsmeshes with the toothed wheel 94 and is arranged on and coaxial to thepiston of a hydraulic motor I00 (Figs. 3a and 5). The index pawl 9|(Fig. 4) is a two-armed lever which is mounted on a bolt I02 (Fig. 4)and has on the end of one arm a nose 91 engaging the notches in theindex plate and on the end of the other arm a contact plate 99 which ispressed constantly'against a contact 92 of a two-wire electric cable 69for the electric magnet I03 (Fig. 9). The cable 69 has a second contact18 (Fig. 2) which, when the index pawl 9| is disengaged, is connected tothe contact 92 by the contactiplate 99. The nose 91 of the index pawl 9|is continually pressed strongly against the index plate 90 by a springI21 (Fig. 4).

The time-relay Index pawl 9| is operated by a hydraulic motor, thepiston IOI of which (Figs. 4, 5) has annular passages H6 and H1 and isconnected to an extension of the pawl 9| by means of a bell crank lever99; the movements of the piston IOI are controlled by a hydraulictime-relay designed as a plunger I06, I06, having annular passages IIIand H2 and being loaded by a spring I01; said plunger is operated byhydraulic pressure the supply of which is adjustable by means of amanually controlled throttle valve IIO.

Passages H3 and I are formed in the indexing mechanism which areconnected to the conduit 64' referred to above (Figs. 1 and 5).

The time-relay plunger I06, I06 and the piston IOI for operating theindex pawl 9| are cooperatively interconnected bypassages II5, 20 andI24; the piston IOI is in turn connected by conduits I2| and I23 to thepiston I00 for actuating the index plate 90. The conduit |2I and itsextension V lead to the front side (Figs. 3a and 5) of the piston I00operating the index plate 90, while the passage I23 and its continuationH lead to the rear side of said piston I00.

Other passages I09, I09, II9, I22, I25 are connected to an overflowconduit II9 which leads to an oil collecting tank I26.

The electric equipment The electric equipment comprises (1) a main,

of which being closed by a wire 13; the other wire of 16 the cable 69leads to an electromagnetic switch 10, the circuit of which is closed bya wire 10 and (3) electric connecting wires 1|, l2 and 14.

The table control the Working piston 58 (Fig. 1), and forces the lattertowards the left. The oil on the left side of the piston 58 fiows backto the collecting tank through the conduits 88, 5| (Figs. 1, 6, 7, 10),the peripheral passage 52 of the sleeve 44 and the conduits 53 and 54.'Pressure oil also passes from the conduit 28 through the passages 33,34, to the right side of the sleeve 44, the left side of which isconnected to the discharge passage 54 by the passages 56, 51, so thatthe sleeve 44 is maintained in its extreme'left position by the liquidpressure. As the conduit 64' leading to the indexing mechanism 22 isunder a slight pressure determined by the ball valve 89, and as cockplug 42, being in the position shown in Figs. 6 and 15, connects theconduit 64 and the discharge conduit 62 through the passage 82, thetime-relay I86 loaded by the spring I81 and pressed by the latter to theright will assume the position shown in Fig. 5.

Operation of the machine When the table 2| moves to the left; and assoon as the abutment 46 (Fig. 1) comes into contact with the lever 45,thecock plugs 4| and 42 and sleeve 44 are turned around in clockwisedirection (Figs. 9 to 15), the control edges of which are so arrangedrelatively to the conduits and passages cooperatively associatedtherewith that the following control operations are performedsuccessively.

(1) The communication of the passages 56, 83 with the discharge conduit51 is interrupted in the plug 4| (Fig. 9), at the same time thecommunication of the passages 55, 84 (Fig. 14) with they pressure oilconduit 34, and of the passages 64, 85 (Fig. 15) with the dischargeconduit 64 is blocked in the cock plug 42. In the meantime the table 2|continues to travel and to turn around said plugs and sleeve, namelywith unreduced speed, since the sleeve 44 (Figs. 10 and 12) turns idlyup to this point and the control edges of the passages 52 and 48 havenot yet reached the passages 53 and 8| respectively.

(2) As soon as the passage 62 (Fig. 15) is completely shut off thepassage 85, the communication between the passages 35 and 85 isestablished as the plugs continue -to turn in clockwise I matically.

(3) The pressure oil reaching the indexing mechanism through the conduit64' passes into the conduits H3 and H4 (Fig. 5) and flows from conduitII4 through the annular space I and the passage II5 to the left side ofthe piston I8| operating the index pawl 9| and shifts the latter to theright, since the right side of the piston I8I is in communicationthrough conduit I28, the annular space 2 of the time-relay I86, I96

and passage III with the overflow 8 and the collecting tank I26. At thesame time the pressure oil flowing through the passage 3 to the rightside of the time-relay I86, I86 forces the latter to the left againstthe pressure of the spring I81; this is accomplished, because the leftside of the time-relay plunger is also in communication with theoverflow passage H9 and the collecting tank I26 through passage I88 andthrottle valve II8 cooperating with the time-relay; said throttle valveis so adjusted that the piston I8I. operating the index pawl 9| hascompleted its travel on reaching its extreme right position, namelybefore the communication of the passage II8 with passage I28 and of thepassages I|4, II5'-established by the annular spaces III and 2 of thetime-relay, is interrupted, and before the passage I24 isi' set free bythe timerelay.

- In the course of the displacement of the piston |8I operating theindex pawl 9| towards the right the latter is disengaged against theaction of the spring |2'| ,(Fig. 4), namely through the intermediarybell crank lever 99 engaging the extension I (Figs. 3 and 5), whereuponthe contact plate 98 of the index pawl 9| will interconnect the contacts18 and 82 immediately after the disengagement has begun, and theelectro-magnet I83 (Figs. 6, 9) will receive current through the cable69 and will pull the shut-off valve 31 instantaneously so far to theright, that the coinmunication of the conduits 32 and 38 is inter-'rupted, while the communication of the annular passage I84 and theconduits 38 and 39 is established.

(4) After the shut-off valve 31 has interconnected the passages 38 and39, thecock plug 4|, rotated by the table 2|, which gradually slowsdown, arrives in a specific position in which the 42 (Figs. 8 and 14),rotated in the same direction, now connects also the right side ofsleeve 44 to the discharge conduit 54 through the passages 55, 84, 6|,the ball valve 89 (Fig. 6) and the passage 63. Because of the surplus ofoil pressure prevailing at the right side of the sleeve 44 and beingcontrolled by the spring loaded ball valve 89, sleeve 44 will remain,axially unmoveable, in

its position, whereupon the table 2| is-by turning around the sleeve44ultimately locked automatically and will: remain in its'extreme leftposition.

After the table 2| has been arrested at the end of its above describedtravel to the left and.- as the piston |8| has reached meanwhile itsextreme right position (Fig. 5a), the time relay plunger by moving tothe left will open the passage I24, so that pressure oil can pass fromthe conduit 64' through the passages II3, I24, 6 and |2| to the frontside of the motor I88 operating the index plate 98. v

While the piston |8| operating the index pawl 9| is in its extreme rightposition (Fig. 5a), and since the rear side H of the piston I88operating the index plate 98 is in communication with the collectingtank I26 through the conduit I23, annular space II! and passage I25, therack 93 is displaced to the left andthroughpinion 9 4, pawl 95 andratchet wheel 96, whereby the workpiece spindle 92 and the index plate98 are revolved.

As the time-relay plunger I86, I86 continues its movement to the leftthe annular space I establishes communication between the conduit 5 andthe conduit I09 soon after'the passage I20 has been opened (Fig. 50.),so that the left side of the piston |0| is connected to the dischargeII9; concurrently the adjacent annular space N2 of thetime-relay'plunger establishes communication between the conduit I I4and passage I20, so that the pressure oil is free to pass to the rightside of the piston |0| operating the index pawl .9I, whereupon thelatter will be pressed against the index plate 90 by the bell cranklever 99 and spring I2'I (Fig. 4).

However, since the piston I00 operating the index plate 90 has justreceived pressure oil, and as theindex plate 90 has already been turnedaround through a small angle, the nose 9! of the pawl 9| will bearagainst the peripheral edge of the index plate 90. Thus the piston |0|operating the index pawl 9| will be advanced to the right very little,namely not more than permitted by the index pawl bearing against theindex plate 90.

(5) While the table 2| is still at rest the index plate 90 continues toturn around under the index pawl 9| through the action of the pressureoil reaching the front side of the piston I00 through the passages II3,I24, 6, IeI and V, so that in accordance to the width of the respectivenotches of the index plate 90 the index pawl 9| will after a while snapinto one of said notches under the action of the spring I2'I-and the oilpressure resting upon the right side of the piston I00. In consequenceof the engagement of the index'pawl 9| in a notch of the index plate 90(Fig. 4) the electric circuit in thecable 68 is interrupted at thecontact point I8, and following the return of the piston IOI into itsextreme left position (Fig. 5), the pressure oil passing throughpassages II3, I24 will proceed through the annular space I I1 and thepassages I23 and H to the rear side of the working piston I00, the frontside of which is in communication with the overflow passage 9 by thepassages V, I2I, annular space I I6 and passage I22, with the resultthat the piston I00 operating the index plate 90 is reversed and returnsinto its initial position.

(6) The indexing operation is finished after the nose 91 of the indexingpawl 9| has engaged the respective notch of the index plate 90.

As the result of the breaking of the electric circuit at the contactsI8, 82 by the engagement of the index pawl 9| in the index plate 90 theshut-off valve 31 loaded by spring S returns into the position, shown inFig. 9, and establishes the communication of the conduit 32 with theconduit 38, whereupon pressure oil flowing through the passages 32, 38,38 and the passages 83, 56 of the revolved cock plug 4| will now reachthe left side of the sleeve 44 (Fig. 8); the latter, being in an angularposition, into which it had been turned by the table abutment 46, and inwhich the table 2| is blocked, is now shifted to the right.

By this longitudinal displacement of the sleeve 44 the table movement isreversed: While sleeve 44 is in its specific displaced position, thepressure oil passes from the passage 20 (Fig. 6) through the throttlevalve I0 and the passages 00, 52, 80,

- 58 (Fig. '7) to the left side of the piston operating the table 2|,concurrently the oil at the right side of the piston 50" escapes intothe discharge conduit 54 (Fig. 6) through the passages 81, 59, 48, andin turn the table 2| re-commences to move to the right.

When the table 2| reaches its extreme right position the cock plugs 4|,42 and the sleeve 44 are turned around back into the positionshown inFig. 1 by an abutment 45' provided at the left end of the table, withthe result, that the table 2| is reversed while the conduits 64, 64 forthe indexing mechanism are in communication with the discharge conduit54; meanwhile the time-relay plunger I00, I06 (Fig. 5) also returns intoits initial extreme right position under the action of the spring I01,so that the whole indexing mechanism is re-set for a fresh cycle ofoperations.

Various changes and modifications may be conveniently made in thestructural details of spline shaft grinding machines of the improveddesign described with reference to Figs. 1 to 15 of the drawings withoutdeparting from the spirit and the salient ideas of this invention.

Instead of a single profiled grinding wheel 24 two or three grindingwheels rotating at high speed may be used to advantage, also tools ofother types including rotary milling cutters may be conveniently usedfor cutting the grooves in the work pieces concerned.

Instead of mounting the indexing mechanism 22 on the reciprocating table2|, as seen in Fig. l, and providing a stationary tool 24, the tool maybe mounted on the reciprocating table, while the work piece and theindexing mechanism are stationarily fixed as seen in Fig. 16 of thedrawings: In the latter the indexing mechanism 22' is secured to themachine bed 20' by screw bolts 1', 2', while the support 24' of thegrinding wheel 24" is fixed at e, e' and carried by the reciprocatingtable 2|" operated by piston 50'.

In this case the pressure oil conduit 84" can be made in the form of anordinary pipe rigidly connecting the indexing mechanism with the controlblock 40', while in the machine shown in Fig. 1 a telescope or otherextensible tube 94' and a flexible cable 69 following the reciprocatingmovements of the indexing mechanism must be provided.

The various other mechanisms shown in Fig. 16 for distributing thepressure oil to the working piston 50' and the indexing mechanism 22'structurally conform to those described with reference to Figs. 1 to 15and designated by the same reference numbers 21 to I03.

What we claim is:

1. In a machine tool having a tool and a table adapted to bereciprocated relatively to each other in rectilinear paths of movement,the combination with a headstock spindle for carrying a work piece to berevolvingly indexed, of a hydraulic indexing mechanism attached to 'saidheadstock spindle for indexing the work piece 'and positively locking itin its indexed position,

another hydraulic mechanism for reciprocating said table, andcontrolling means cooperatively interengaging said hydraulic mechanismsfor locking the table until the work piece has been locked in itsindexed position, said reciprocating mechanism comprising a pistonattached to said table and means for alternately distributing oil underpressure to opposite sides of said piston, said controlling meanscomprising a shut-off valve and an electromagnet operating the latterand cooperatively associating the said indexing mechanism anddistributing means, the latter comprising a rotary spline shaft adaptedto be revolvingly reciprocated by the table, a pair of recessed cockplugs coaxially fixed on said spline shaft, and a recessed sleeveslidably fixed on said spline shaft between said cock plugs forcooperation with the latter.

2. a machine tool having a tool and a table adapted to be reciprocatedrelatively to each other in rectilinear paths of movement, the

' combination with a headstock spindle for carrying a work piece to berevolvingly indexed, of

' engaging the said headstock spindle and in turn revolving said indexplate, a piston for actuating said ratchet mechanism, another piston foractuating said index pawl, and a time-relay for controlling theadmission of oil under pressure to said piston.

3. In a machine tool having a tool and a table adapted to bereciprocated relatively to each other in rectilinear paths of movement,the combination with a headstock spindle for carrying a work piece to berevolvingly indexed, of a hydraulic indexing mechanism attached to saidheadstock spindle for indexing the work piece and positively looking itin its indexed position, another hydraulic mecha m forreciprocating'said table, and controlling means cooperativelyinterengaging said hydraulic mechanisms for locking the table until thework piece has been locked in its indexed position, said indexingmechanism comprising a circumferentially notched index plate, an indexpawl adapted to engage the notches 0! said plate, a ratchet mechanismen- .,gagingthesaidheadstockspindleandintum revolving said index plate,a piston tor actuating said ratchet mechanism, another piston foractuating said index pawl, and a time-relay for controlling theadmission ofoil under pressure to said pistons, said index pawlcomprisinga double armed lever loaded by a spring, acircuit making andbreaking plate for cooperation with said controlling means, and a bellcrank lever interengaging said lever and the piston actuating the indexpawl.

4. In a machine tool having a tool and a table adapted to bereciprocated relatively to each other in rectilinear paths of movement,the combination with a headstock spindle for carrying a work piece to berevolvingly indexed, 01' a hydraulic indexing mechanism. attached tosaid headstock spindle for indexing the work piece and positivelylocking it in its indexed position, another hydraulic mechanism forreciprocating said table, and controlling means cooperativelyinterengaging said hydraulic mechanisms for locking the table until thework piece has been locked in its indexed position, said indexingmechanism comprising a circumferentially notched index plate, an indexpawl adapted to engage the notches of said plate, a ratchet mechanismengaging the said headstock spindle and in turn revolving said indexplate, a piston for actuating said ratchet mechanism, another piston foractuating said index pawl, and a time-relay for controlling theadmission of oil under pressure p to said pistons, said time-relaycomprising a

